NIFI-145

nar-bundles/framework-bundle/framework/runtime/src/main/java/org/apache/nifi/BootstrapListener.java

@@ -0,0 +1,229 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.nifi;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.OutputStream;
+import java.net.InetSocketAddress;
+import java.net.ServerSocket;
+import java.net.Socket;
+import java.nio.charset.StandardCharsets;
+import java.util.Arrays;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class BootstrapListener {
+	private static final Logger logger = LoggerFactory.getLogger(BootstrapListener.class);
+	
+	private final NiFi nifi;
+	private final int bootstrapPort;
+
+	private Listener listener;
+	private ServerSocket serverSocket;
+	
+	
+	public BootstrapListener(final NiFi nifi, final int port) {
+		this.nifi = nifi;
+		this.bootstrapPort = port;
+	}
+	
+	public void start() throws IOException {
+		logger.debug("Starting Bootstrap Listener to communicate with Bootstrap Port {}", bootstrapPort);
+		
+		serverSocket = new ServerSocket();
+		serverSocket.bind(new InetSocketAddress("localhost", 0));
+		
+		final int localPort = serverSocket.getLocalPort();
+		logger.info("Started Bootstrap Listener, Listening for incoming requests on port {}", localPort);
+		
+		listener = new Listener(serverSocket);
+		final Thread listenThread = new Thread(listener);
+		listenThread.setName("Listen to Bootstrap");
+		listenThread.start();
+		
+		logger.debug("Notifying Bootstrap that local port is {}", localPort);
+		try (final Socket socket = new Socket()) {
+			socket.setSoTimeout(60000);
+			socket.connect(new InetSocketAddress("localhost", bootstrapPort));
+			socket.setSoTimeout(60000);
+			
+			final OutputStream out = socket.getOutputStream();
+			out.write(("PORT " + localPort + "\n").getBytes(StandardCharsets.UTF_8));
+			out.flush();
+			
+			logger.debug("Awaiting response from Bootstrap...");
+			final BufferedReader reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
+			final String response = reader.readLine();
+			if ("OK".equals(response)) {
+				logger.info("Successfully initiated communication with Bootstrap");
+			} else {
+				logger.error("Failed to communicate with Bootstrap. Bootstrap may be unable to issue or receive commands from NiFi");
+			}
+		}
+	}
+	
+	
+	public void stop() {
+		if (listener != null) {
+			listener.stop();
+		}
+	}
+	
+	private class Listener implements Runnable {
+		private final ServerSocket serverSocket;
+		private final ExecutorService executor;
+		private volatile boolean stopped = false;
+		
+		public Listener(final ServerSocket serverSocket) {
+			this.serverSocket = serverSocket;
+			this.executor = Executors.newFixedThreadPool(2);
+		}
+		
+		public void stop() {
+			stopped = true;
+			
+			executor.shutdownNow();
+			
+			try {
+				serverSocket.close();
+			} catch (final IOException ioe) {
+				// nothing to really do here. we could log this, but it would just become
+				// confusing in the logs, as we're shutting down and there's no real benefit
+			}
+		}
+		
+		@Override
+		public void run() {
+			while (!serverSocket.isClosed()) {
+				try {
+					if ( stopped ) {
+						return;
+					}
+					
+					final Socket socket;
+					try {
+						socket = serverSocket.accept();
+					} catch (final IOException ioe) {
+						if ( stopped ) {
+							return;
+						}
+						
+						throw ioe;
+					}
+					
+					executor.submit(new Runnable() {
+						@Override
+						public void run() {
+							try {
+								final BootstrapRequest request = readRequest(socket.getInputStream());
+								final BootstrapRequest.RequestType requestType = request.getRequestType();
+								
+								switch (requestType) {
+									case PING:
+										logger.debug("Received PING request from Bootstrap; responding");
+										echoPing(socket.getOutputStream());
+										logger.debug("Responded to PING request from Bootstrap");
+										break;
+									case SHUTDOWN:
+										logger.info("Received SHUTDOWN request from Bootstrap");
+										echoShutdown(socket.getOutputStream());
+										nifi.shutdownHook();
+										return;
+								}
+							} catch (final Throwable t) {
+								logger.error("Failed to process request from Bootstrap due to " + t.toString(), t);
+							} finally {
+								try {
+									socket.close();
+								} catch (final IOException ioe) {
+									logger.warn("Failed to close socket to Bootstrap due to {}", ioe.toString());
+								}
+							}
+						}
+					});
+				} catch (final Throwable t) {
+					logger.error("Failed to process request from Bootstrap due to " + t.toString(), t);
+				}
+			}
+		}
+	}
+	
+	
+	private void echoPing(final OutputStream out) throws IOException {
+		out.write("PING\n".getBytes(StandardCharsets.UTF_8));
+		out.flush();
+	}
+	
+	private void echoShutdown(final OutputStream out) throws IOException {
+		out.write("SHUTDOWN\n".getBytes(StandardCharsets.UTF_8));
+		out.flush();
+	}
+	
+	private BootstrapRequest readRequest(final InputStream in) throws IOException {
+		final BufferedReader reader = new BufferedReader(new InputStreamReader(in));
+		
+		final String line = reader.readLine();
+		final String[] splits = line.split(" ");
+		if ( splits.length < 0 ) {
+			throw new IOException("Received invalid command from NiFi: " + line);
+		}
+		
+		final String requestType = splits[0];
+		final String[] args;
+		if ( splits.length == 1 ) {
+			args = new String[0];
+		} else {
+			args = Arrays.copyOfRange(splits, 1, splits.length);
+		}
+		
+		try {
+			return new BootstrapRequest(requestType, args);
+		} catch (final Exception e) {
+			throw new IOException("Received invalid request from bootstrap; request type = " + requestType);
+		}
+	}
+	
+	
+	private static class BootstrapRequest {
+		public static enum RequestType {
+			SHUTDOWN,
+			PING;
+		}
+		
+		private final RequestType requestType;
+		private final String[] args;
+		
+		public BootstrapRequest(final String request, final String[] args) {
+			this.requestType = RequestType.valueOf(request);
+			this.args = args;
+		}
+		
+		public RequestType getRequestType() {
+			return requestType;
+		}
+		
+		public String[] getArgs() {
+			return args;
+		}
+	}
+}

nar-bundles/framework-bundle/framework/runtime/src/main/java/org/apache/nifi/NiFi.java

@@ -45,6 +45,9 @@ public class NiFi {
 
     private static final Logger logger = LoggerFactory.getLogger(NiFi.class);
     private final NiFiServer nifiServer;
+    private final BootstrapListener bootstrapListener;
+    
+    public static final String BOOTSTRAP_PORT_PROPERTY = "nifi.bootstrap.listen.port";
 
     public NiFi(final NiFiProperties properties) throws ClassNotFoundException, IOException, NoSuchMethodException, InstantiationException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {
         Thread.setDefaultUncaughtExceptionHandler(new UncaughtExceptionHandler() {
@@ -65,6 +68,25 @@ public class NiFi {
             }
         }));
 
+        final String bootstrapPort = System.getProperty(BOOTSTRAP_PORT_PROPERTY);
+        if ( bootstrapPort != null ) {
+        	try {
+        		final int port = Integer.parseInt(bootstrapPort);
+        		
+        		if (port < 1 || port > 65535) {
+        			throw new RuntimeException("Failed to start NiFi because system property '" + BOOTSTRAP_PORT_PROPERTY + "' is not a valid integer in the range 1 - 65535");
+        		}
+        		
+        		bootstrapListener = new BootstrapListener(this, port);
+        		bootstrapListener.start();
+        	} catch (final NumberFormatException nfe) {
+        		throw new RuntimeException("Failed to start NiFi because system property '" + BOOTSTRAP_PORT_PROPERTY + "' is not a valid integer in the range 1 - 65535");
+        	}
+        } else {
+        	logger.info("NiFi started without Bootstrap Port information provided; will not listen for requests from Bootstrap");
+        	bootstrapListener = null;
+        }
+        
         // delete the web working dir - if the application does not start successfully
         // the web app directories might be in an invalid state. when this happens
         // jetty will not attempt to re-extract the war into the directory. by removing
@@ -115,6 +137,9 @@ public class NiFi {
             if (nifiServer != null) {
                 nifiServer.stop();
             }
+            if (bootstrapListener != null) {
+            	bootstrapListener.stop();
+            }
             logger.info("Jetty web server shutdown completed (nicely or otherwise).");
         } catch (final Throwable t) {
             logger.warn("Problem occured ensuring Jetty web server was properly terminated due to " + t);

nifi-bootstrap/pom.xml

@@ -1,5 +1,18 @@
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<!--
+      Licensed to the Apache Software Foundation (ASF) under one or more
+      contributor license agreements.  See the NOTICE file distributed with
+      this work for additional information regarding copyright ownership.
+      The ASF licenses this file to You under the Apache License, Version 2.0
+      (the "License"); you may not use this file except in compliance with
+      the License.  You may obtain a copy of the License at
+          http://www.apache.org/licenses/LICENSE-2.0
+      Unless required by applicable law or agreed to in writing, software
+      distributed under the License is distributed on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+      See the License for the specific language governing permissions and
+      limitations under the License.
+    -->
 	<modelVersion>4.0.0</modelVersion>
 
 	<parent>

nifi-bootstrap/src/main/java/org/apache/nifi/bootstrap/BootstrapCodec.java

@@ -0,0 +1,89 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.nifi.bootstrap;
+
+import java.io.BufferedReader;
+import java.io.BufferedWriter;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.OutputStream;
+import java.io.OutputStreamWriter;
+import java.util.Arrays;
+
+import org.apache.nifi.bootstrap.exception.InvalidCommandException;
+
+public class BootstrapCodec {
+	private final RunNiFi runner;
+	private final BufferedReader reader;
+	private final BufferedWriter writer;
+	
+	public BootstrapCodec(final RunNiFi runner, final InputStream in, final OutputStream out) {
+		this.runner = runner;
+		this.reader = new BufferedReader(new InputStreamReader(in));
+		this.writer = new BufferedWriter(new OutputStreamWriter(out));
+	}
+	
+	public void communicate() throws IOException {
+		final String line = reader.readLine();
+		final String[] splits = line.split(" ");
+		if ( splits.length < 0 ) {
+			throw new IOException("Received invalid command from NiFi: " + line);
+		}
+		
+		final String cmd = splits[0];
+		final String[] args;
+		if ( splits.length == 1 ) {
+			args = new String[0];
+		} else {
+			args = Arrays.copyOfRange(splits, 1, splits.length);
+		}
+		
+		try {
+			processRequest(cmd, args);
+		} catch (final InvalidCommandException ice) {
+			throw new IOException("Received invalid command from NiFi: " + line + " : " + ice.getMessage() == null ? "" : "Details: " + ice.toString());
+		}
+	}
+
+	private void processRequest(final String cmd, final String[] args) throws InvalidCommandException, IOException {
+		switch (cmd) {
+			case "PORT": {
+				if ( args.length != 1 ) {
+					throw new InvalidCommandException();
+				}
+				
+				final int port;
+				try {
+					port = Integer.parseInt( args[0] );
+				} catch (final NumberFormatException nfe) {
+					throw new InvalidCommandException("Invalid Port number; should be integer between 1 and 65535");
+				}
+				
+				if ( port < 1 || port > 65535 ) {
+					throw new InvalidCommandException("Invalid Port number; should be integer between 1 and 65535");
+				}
+				
+				runner.setNiFiCommandControlPort(port);
+				writer.write("OK");
+				writer.newLine();
+				writer.flush();
+			}
+			break;
+		}
+	}
+}

nifi-bootstrap/src/main/java/org/apache/nifi/bootstrap/NiFiListener.java

@@ -0,0 +1,116 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.nifi.bootstrap;
+
+import java.io.IOException;
+import java.net.InetSocketAddress;
+import java.net.ServerSocket;
+import java.net.Socket;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+
+public class NiFiListener {
+	private ServerSocket serverSocket;
+	private volatile Listener listener;
+	
+	int start(final RunNiFi runner) throws IOException {
+		serverSocket = new ServerSocket();
+		serverSocket.bind(new InetSocketAddress("localhost", 0));
+		
+		final int localPort = serverSocket.getLocalPort();
+		listener = new Listener(serverSocket, runner);
+		final Thread listenThread = new Thread(listener);
+		listenThread.setName("Listen to NiFi");
+		listenThread.start();
+		return localPort;
+	}
+	
+	public void stop() throws IOException {
+		final Listener listener = this.listener;
+		if ( listener == null ) {
+			return;
+		}
+		
+		listener.stop();
+	}
+	
+	private class Listener implements Runnable {
+		private final ServerSocket serverSocket;
+		private final ExecutorService executor;
+		private final RunNiFi runner;
+		private volatile boolean stopped = false;
+		
+		public Listener(final ServerSocket serverSocket, final RunNiFi runner) {
+			this.serverSocket = serverSocket;
+			this.executor = Executors.newFixedThreadPool(2);
+			this.runner = runner;
+		}
+		
+		public void stop() throws IOException {
+			stopped = true;
+			
+			executor.shutdown();
+			try {
+				executor.awaitTermination(3, TimeUnit.SECONDS);
+			} catch (final InterruptedException ie) {
+			}
+			
+			serverSocket.close();
+		}
+		
+		@Override
+		public void run() {
+			while (!serverSocket.isClosed()) {
+				try {
+					if ( stopped ) {
+						return;
+					}
+					
+					final Socket socket;
+					try {
+						socket = serverSocket.accept();
+					} catch (final IOException ioe) {
+						if ( stopped ) {
+							return;
+						}
+						
+						throw ioe;
+					}
+					
+					
+					executor.submit(new Runnable() {
+						@Override
+						public void run() {
+							try {
+								final BootstrapCodec codec = new BootstrapCodec(runner, socket.getInputStream(), socket.getOutputStream());
+								codec.communicate();
+								socket.close();
+							} catch (final Throwable t) {
+								System.out.println("Failed to communicate with NiFi due to " + t);
+								t.printStackTrace();
+							}
+						}
+					});
+				} catch (final Throwable t) {
+					System.err.println("Failed to receive information from NiFi due to " + t);
+					t.printStackTrace();
+				}
+			}
+		}
+	}
+}

nifi-bootstrap/src/main/java/org/apache/nifi/bootstrap/RunNiFi.java

@@ -1,16 +1,45 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
 package org.apache.nifi.bootstrap;
 
+import java.io.BufferedReader;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
 import java.io.FilenameFilter;
 import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.OutputStream;
+import java.net.InetSocketAddress;
+import java.net.Socket;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Properties;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.Condition;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReentrantLock;
 
 
 /**
@@ -18,7 +47,6 @@ import java.util.Properties;
  * 
  * This class looks for the bootstrap.conf file by looking in the following places (in order):
  * <ol>
- * 	<li>First argument to the program</li>
  *  <li>Java System Property named {@code org.apache.nifi.bootstrap.config.file}</li>
  *  <li>${NIFI_HOME}/./conf/bootstrap.conf, where ${NIFI_HOME} references an environment variable {@code NIFI_HOME}</li>
  *  <li>./conf/bootstrap.conf, where {@code .} represents the working directory.
@@ -29,12 +57,57 @@ import java.util.Properties;
 public class RunNiFi {
 	public static final String DEFAULT_CONFIG_FILE = "./conf/boostrap.conf";
 	public static final String DEFAULT_NIFI_PROPS_FILE = "./conf/nifi.properties";
-	
-	@SuppressWarnings({ "rawtypes", "unchecked" })
-	public static void main(final String[] args) throws IOException, InterruptedException {
-		final ProcessBuilder builder = new ProcessBuilder();
 
-		String configFilename = (args.length > 0) ? args[0] : System.getProperty("org.apache.nifi.boostrap.config.file");
+	public static final int MAX_RESTART_ATTEMPTS = 5;
+	public static final int STARTUP_WAIT_SECONDS = 60;
+	
+	public static final String SHUTDOWN_CMD = "SHUTDOWN";
+	public static final String PING_CMD = "PING";
+	
+	private volatile boolean autoRestartNiFi = true;
+	private volatile int ccPort = -1;
+	
+	private final Lock lock = new ReentrantLock();
+	private final Condition startupCondition = lock.newCondition();
+	
+	private final File bootstrapConfigFile;
+	
+	public RunNiFi(final File bootstrapConfigFile) {
+		this.bootstrapConfigFile = bootstrapConfigFile;
+	}
+	
+	private static void printUsage() {
+		System.out.println("Usage:");
+		System.out.println();
+		System.out.println("java org.apache.nifi.bootstrap.RunNiFi <command>");
+		System.out.println();
+		System.out.println("Valid commands include:");
+		System.out.println("");
+		System.out.println("Start : Start a new instance of Apache NiFi");
+		System.out.println("Stop : Stop a running instance of Apache NiFi");
+		System.out.println("Status : Determine if there is a running instance of Apache NiFi");
+		System.out.println();
+	}
+	
+	public static void main(final String[] args) throws IOException, InterruptedException {
+		if ( args.length != 1 ) {
+			printUsage();
+			return;
+		}
+		
+		switch (args[0].toLowerCase()) {
+			case "start":
+			case "stop":
+			case "status":
+				break;
+			default:
+				System.out.println("Invalid argument: " + args[0]);
+				System.out.println();
+				printUsage();
+				return;
+		}
+		
+		String configFilename = System.getProperty("org.apache.nifi.boostrap.config.file");
 		
 		if ( configFilename == null ) {
 			final String nifiHome = System.getenv("NIFI_HOME");
@@ -50,12 +123,122 @@ public class RunNiFi {
 		}
 		
 		final File configFile = new File(configFilename);
-		if ( !configFile.exists() ) {
+		
+		final RunNiFi runNiFi = new RunNiFi(configFile);
+		
+		switch (args[0].toLowerCase()) {
+			case "start":
+				runNiFi.start();
+				break;
+			case "stop":
+				runNiFi.stop();
+				break;
+			case "status":
+				runNiFi.status();
+				break;
+		}
+	}
+	
+	
+	public File getStatusFile() {
+		final File rootDir = bootstrapConfigFile.getParentFile();
+		final File statusFile = new File(rootDir, "nifi.port");
+		return statusFile;
+	}
+
+	private Integer getCurrentPort() throws IOException {
+		try {
+			final File statusFile = getStatusFile();
+			final byte[] info = Files.readAllBytes(statusFile.toPath());
+			final String text = new String(info);
+			
+			final int port = Integer.parseInt(text);
+			
+			try (final Socket socket = new Socket("localhost", port)) {
+				final OutputStream out = socket.getOutputStream();
+				out.write((PING_CMD + "\n").getBytes(StandardCharsets.UTF_8));
+				out.flush();
+				
+				final InputStream in = socket.getInputStream();
+				final BufferedReader reader = new BufferedReader(new InputStreamReader(in));
+				final String response = reader.readLine();
+				if ( response.equals(PING_CMD) ) {
+					return port;
+				}
+			} catch (final IOException ioe) {
+				System.out.println("Found NiFi instance info at " + statusFile + " but information appears to be stale. Removing file.");
+				if ( !statusFile.delete() ) {
+					System.err.println("Unable to remove status file");
+				}
+				
+				throw ioe;
+			}
+		} catch (final Exception e) {
+			return null;
+		}
+		
+		return null;
+	}
+	
+	
+	public void status() throws IOException {
+		final Integer port = getCurrentPort();
+		if ( port == null ) {
+			System.out.println("Apache NiFi does not appear to be running");
+		} else {
+			System.out.println("Apache NiFi is currently running, listening on port " + port);
+		}
+		return;
+	}
+	
+	
+	public void stop() throws IOException {
+		final Integer port = getCurrentPort();
+		if ( port == null ) {
+			System.out.println("Apache NiFi is not currently running");
+			return;
+		}
+		
+		try (final Socket socket = new Socket()) {
+			socket.setSoTimeout(60000);
+			socket.connect(new InetSocketAddress("localhost", port));
+			socket.setSoTimeout(60000);
+			
+			final OutputStream out = socket.getOutputStream();
+			out.write((SHUTDOWN_CMD + "\n").getBytes(StandardCharsets.UTF_8));
+			out.flush();
+			
+			final InputStream in = socket.getInputStream();
+			final BufferedReader reader = new BufferedReader(new InputStreamReader(in));
+			final String response = reader.readLine();
+			if ( SHUTDOWN_CMD.equals(response) ) {
+				System.out.println("Apache NiFi has accepted the Shutdown Command and is shutting down now");
+			} else {
+				System.err.println("When sending SHUTDOWN command to NiFi, got unexpected response " + response);
+			}
+		} catch (final IOException ioe) {
+			System.err.println("Failed to communicate with Apache NiFi");
+			return;
+		}
+	}
+	
+	
+	@SuppressWarnings({ "rawtypes", "unchecked" })
+	public void start() throws IOException, InterruptedException {
+		final Integer port = getCurrentPort();
+		if ( port != null ) {
+			System.out.println("Apache NiFi is already running, listening on port " + port);
+			return;
+		}
+		
+		final ProcessBuilder builder = new ProcessBuilder();
+
+		if ( !bootstrapConfigFile.exists() ) {
 			throw new FileNotFoundException(DEFAULT_CONFIG_FILE);
 		}
 		
 		final Properties properties = new Properties();
-		try (final FileInputStream fis = new FileInputStream(configFile)) {
+		try (final FileInputStream fis = new FileInputStream(bootstrapConfigFile)) {
 			properties.load(fis);
 		}
 		
@@ -136,32 +319,67 @@ public class RunNiFi {
 			javaCmd = "java";
 		}
 		
+		final NiFiListener listener = new NiFiListener();
+		final int listenPort = listener.start(this);
+		
 		final List<String> cmd = new ArrayList<>();
 		cmd.add(javaCmd);
 		cmd.add("-classpath");
 		cmd.add(classPath);
 		cmd.addAll(javaAdditionalArgs);
 		cmd.add("-Dnifi.properties.file.path=" + nifiPropsFilename);
+		cmd.add("-Dnifi.bootstrap.listen.port=" + listenPort);
 		cmd.add("org.apache.nifi.NiFi");
 		
-		builder.command(cmd).inheritIO();
+		builder.command(cmd);
 		
 		final StringBuilder cmdBuilder = new StringBuilder();
 		for ( final String s : cmd ) {
 			cmdBuilder.append(s).append(" ");
 		}
+
 		System.out.println("Starting Apache NiFi...");
 		System.out.println("Working Directory: " + workingDir.getAbsolutePath());
 		System.out.println("Command: " + cmdBuilder.toString());
-
-		final Process proc = builder.start();
-		Runtime.getRuntime().addShutdownHook(new ShutdownHook(proc));
-		final int statusCode = proc.waitFor();
-		System.out.println("Apache NiFi exited with Status Code " + statusCode);
+		
+		builder.start();
+		boolean started = waitForStart();
+		
+		if ( started ) {
+			System.out.println("Successfully started Apache NiFi");
+		} else {
+			System.err.println("Apache NiFi does not appear to have started");
+		}
+		
+		listener.stop();
 	}
 	
 	
-	private static File getFile(final String filename, final File workingDir) {
+	private boolean waitForStart() {
+		lock.lock();
+		try {
+			final long startTime = System.nanoTime();
+			
+			while ( ccPort < 1 ) {
+				try {
+					startupCondition.await(1, TimeUnit.SECONDS);
+				} catch (final InterruptedException ie) {
+					return false;
+				}
+				
+				final long waitNanos = System.nanoTime() - startTime;
+				final long waitSeconds = TimeUnit.NANOSECONDS.toSeconds(waitNanos);
+				if (waitSeconds > STARTUP_WAIT_SECONDS) {
+					return false;
+				}
+			}
+		} finally {
+			lock.unlock();
+		}
+		return true;
+	}
+	
+	private File getFile(final String filename, final File workingDir) {
 		File libDir = new File(filename);
 		if ( !libDir.isAbsolute() ) {
 			libDir = new File(workingDir, filename);
@@ -170,7 +388,29 @@ public class RunNiFi {
 		return libDir;
 	}
 	
-	private static String replaceNull(final String value, final String replacement) {
+	private String replaceNull(final String value, final String replacement) {
 		return (value == null) ? replacement : value;
 	}
+	
+	void setAutoRestartNiFi(final boolean restart) {
+		this.autoRestartNiFi = restart;
+	}
+	
+	void setNiFiCommandControlPort(final int port) {
+		this.ccPort = port;
+
+		final File statusFile = getStatusFile();
+		try (final FileOutputStream fos = new FileOutputStream(statusFile)) {
+			fos.write(String.valueOf(port).getBytes(StandardCharsets.UTF_8));
+			fos.getFD().sync();
+		} catch (final IOException ioe) {
+			System.err.println("Apache NiFi has started but failed to persist NiFi Port information to " + statusFile.getAbsolutePath() + " due to " + ioe);
+		}
+		
+		System.out.println("Apache NiFi now running and listening for requests on port " + port);
+	}
+	
+	int getNiFiCommandControlPort() {
+		return this.ccPort;
+	}
 }

nifi-bootstrap/src/main/java/org/apache/nifi/bootstrap/ShutdownHook.java

@@ -1,14 +1,71 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
 package org.apache.nifi.bootstrap;
 
+import java.io.File;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.net.Socket;
+import java.nio.charset.StandardCharsets;
+import java.util.concurrent.TimeUnit;
+
 public class ShutdownHook extends Thread {
 	private final Process nifiProcess;
+	private final RunNiFi runner;
 	
-	public ShutdownHook(final Process nifiProcess) {
+	public static final int WAIT_SECONDS = 10;
+	
+	public ShutdownHook(final Process nifiProcess, final RunNiFi runner) {
 		this.nifiProcess = nifiProcess;
+		this.runner = runner;
 	}
 	
 	@Override
 	public void run() {
+		runner.setAutoRestartNiFi(false);
+		final int ccPort = runner.getNiFiCommandControlPort();
+		if ( ccPort > 0 ) {
+			System.out.println("Initiating Shutdown of NiFi...");
+			
+			try {
+				final Socket socket = new Socket("localhost", ccPort);
+				final OutputStream out = socket.getOutputStream();
+				out.write("SHUTDOWN\n".getBytes(StandardCharsets.UTF_8));
+				out.flush();
+				
+				socket.close();
+			} catch (final IOException ioe) {
+				System.out.println("Failed to Shutdown NiFi due to " + ioe);
+			}
+		}
+		
+		try {
+			nifiProcess.waitFor(WAIT_SECONDS, TimeUnit.SECONDS);
+		} catch (final InterruptedException ie) {
+		}
+
+		if ( nifiProcess.isAlive() ) {
+			System.out.println("NiFi has not finished shutting down after " + WAIT_SECONDS + " seconds. Killing process.");
+		}
 		nifiProcess.destroy();
+		
+		final File statusFile = runner.getStatusFile();
+		if ( !statusFile.delete() ) {
+			System.err.println("Failed to delete status file " + statusFile.getAbsolutePath());
+		}
 	}
 }

nifi-bootstrap/src/main/java/org/apache/nifi/bootstrap/exception/InvalidCommandException.java

@@ -0,0 +1,37 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.nifi.bootstrap.exception;
+
+public class InvalidCommandException extends Exception {
+	private static final long serialVersionUID = 1L;
+
+	public InvalidCommandException() {
+		super();
+	}
+	
+	public InvalidCommandException(final String message) {
+		super(message);
+	}
+	
+	public InvalidCommandException(final Throwable t) {
+		super(t);
+	}
+	
+	public InvalidCommandException(final String message, final Throwable t) {
+		super(message, t);
+	}
+}